Engineering topics

Zhang, Qiaobao

Publications and source records attributed to Zhang, Qiaobao.

5 records

DOE OSTI2024

Hard carbon with an opened pore structure for enhanced sodium storage performance

The pore structure of hard carbon has a significant impact on its Na + storage capacity. Herein, a waste wood-derived hard carbon with opened pores (OP-HC) was fabricated with polyvinyl pyrrolidone (PVP) as an additive. Ex situ SAXS and HR-TEM testing results indicate that OP-HC with opened pores and enlarged d 002 interlayer spacing facilitates the reversible (de)sodiation of Na + ions. In situ TEM and XRD testing results demonstrate that OP-HC shows excellent structure stability during the (de)sodiation process. Thus, OP-HC delivers a high reversible charge capacity of 350.7 mA h g −1 at 0.05 C and an ultra-high initial Coulombic efficiency (ICE) of 94.9%. Moreover, OP-HC exhibits excellent cycling stability, and the assembled 18650 full cell with an OP-HC anode can achieve a high capacity retention of 94.5% after 400 cycles at 1.0 A. Furthermore, the excellent electrochemical performance and deep insights into OP-HC with opened pores and increased d 002 interlayer spacing offer a new strategy to design high-performance HC anodes for SIBs.

You, Shunzhang↗

DOE OSTI2024

Sustainable layered cathode with suppressed phase transition for long-life sodium-ion batteries

Sodium-ion batteries are among the most promising alternatives to lithium-based technologies for grid and other energy storage applications due to their cost benefits and sustainable resource supply. For the cathode—the component that largely determines the energy density of a sodium-ion battery cell—one major category of materials is P2-type layered oxides. Unfortunately, at high state-of-charge, such materials tend to undergo a phase transition with a very large volume change and consequent structural degradation during long-term cycling. Here we address this issue by introducing vacancies into the transition metal layer of P2-Na$_{0.7}$Fe$_{0.1}$Mn$_{0.75\square}$$_{0.15}$O2 (‘$_{\square}$’ represents a vacancy). The transition metal vacancy serves to suppress migration of neighbouring Na ions and therefore maintain structural and thermal stability in Na-depleted states. Moreover, the specific Na-O-$_{\square}$ configuration triggers a reversible anionic redox reaction and boosts the energy density. As a result, the cathode design here enables pouch cells with energy densities of 170 Wh kg -1 and 120 Wh kg -1 that can operate for over 600 and 1,000 cycles, respectively. In conclusion, our work not only suggests a feasible strategy for cathode design but also confirms the possibility of developing a battery chemistry that features a reduced need for critical raw materials.

25 ENERGY STORAGE↗

DOE OSTI2023

Implanting Transition Metal into Li 2 O-Based Cathode Prelithiation Agent for High-Energy-Density and Long-Life Li-Ion Batteries

Compensating the irreversible loss of limited active lithium (Li) is essentially important for improving the energy-density and cycle-life of practical Li-ion battery full-cell, especially after employing high-capacity but low initial coulombic efficiency anode candidates. Introducing prelithiation agent can provide additional Li source for such compensation. Herein, we precisely implant trace Co (extracted from transition metal oxide) into the Li site of Li 2 O, obtaining (Li 0.66 Co 0.11$\square$0.23 ) 2 O (CLO) cathode prelithiation agent. Further, the synergistic formation of Li vacancies and Co-derived catalysis efficiently enhance the inherent conductivity and weaken the Li-O interaction of Li 2 O, which facilitates its anionic oxidation to peroxo/superoxo species and gaseous O 2 , achieving 1642.7 mAh/g ~Li2O prelithiation capacity (≈980 mAh/g for prelithiation agent). Coupled 6.5 wt % CLO-based prelithiation agent with LiCoO 2 cathode, substantial additional Li source stored within CLO is efficiently released to compensate the Li consumption on the SiO/C anode, achieving 270 Wh/kg pouch-type full-cell with 92 % capacity retention after 1000 cycles.

25 ENERGY STORAGE↗

DOE OSTI2021

Quantifying the reaction mechanisms of a high-capacity CuP 2 /C composite anode for potassium ion batteries

Introducing metals into phosphorus to form metal phosphide materials as anodes for potassium ion batteries (PIBs) is an effective strategy to improve the electronic conductivity and alleviate the volume change during cycling, although with a compromise of capacity. Here in this paper, we explore a CuP 2 /C composite as a novel anode for PIBs, which delivers a high reversible capacity of >450 mA h g -1 . Unexpectedly, our results reveal that the POx components existing in the prepared composite are reversible, through a quantitative analysis via high-resolution solid-state 31 P NMR and synchrotron X-ray diffraction tests. Their potassiation products K 3 PO 4 and K 4 P 2 O 7 can react with K–P alloys and turn back to PO x during depotassiation, which probably accounts for the high capacity of the prepared material. The results also illustrate a crystallization–amorphization evolution process during cycling involving nanocrystalline α-K 4 P 6 , K 4 P 3 and KP, and amorphous K 4 P 6 , KP and K 3 P phases, among which, the amorphous phases are identified for the first time.

25 ENERGY STORAGE↗

DOE OSTI2020

Surface Amorphization of Vanadium Dioxide (B) for K-ion Battery

Given the merits of low cost, fast ionic transport in electrolyte, and high operating voltage, potassium ion batteries (PIBs) are promising alternatives to lithium-ion batteries. However, developing suitable electrode materials that can reversibly accommodate large potassium ions is a great challenge. In this paper, guided by density functional theory (DFT) calculations, it is demonstrated that the strategy of interfacial engineering via surface amorphization of VO 2 (B) nanorods (SA-VO 2 ), which results in the formation of a crystalline core/amorphous shell heterostructure, enables superior K + storage performance in terms of large capacity, outstanding rate capability, and long cycle stability working as an anode for PIBs. DFT calculations reveal that the created crystalline/amorphous heterointerface in SA-VO 2 can substantially lower the surface energy, narrow the band gap, and reduce the K + diffusion barrier of VO 2 (B). These conditions enable enhanced K + storage capacity and rapid K + /electron transfer, which result in large capacity and outstanding rate capability. Using in situ X-ray diffraction and in situ transmission electron microscopy complemented by ex situ microscopic and spectroscopic techniques, it is unveiled that the superior cycling stability originates from the excellent phase reversibility with negligible strain response and robust mechanical behavior of SA-VO 2 upon (de)potassiation.

25 ENERGY STORAGE↗